Fluid pressure engines



Jan. 17, 1956 A. DOBLE FLUID PRESSURE ENGINES Filed April 7, 1952 2 Sheets-Sheet l INVENTOR.

Jan. 17, 1956 A. DOBLE FLUID PRESSURE ENGINES Filed April '7, 1952 so 49 4a as l2! 2 Sheets-Sheet 2 {Egg- Ale/Y5? 00.5.45,

IN VEN TOR.

, rraewe/ United States Patent FLUID PRESURE ENGINES Abner Doble, Santa Rosa, fialii, assignor to McCulloch Motors Corporation, Los Angeies, Caiii, a corporation of Wisconsin Application April 7, 1952, Seriai No. zsaavs 7 Claims. or. 121-102 This invention relates to fluid pressure engines of the Woolf type, and relates in particular to improvements in compound uniflow reversing steam engines having single acting high pressure and low pressure pistons inner-connected so that they act in unison, the high pressure piston being effective in one stroke direction and the low pressure piston being effective in the opposite stroke direction, thus giving double acting effects with single acting pistons.

It is an object of the invention to provide a simple engine construction wherein fluid pressures on the opposite ends of the high pressure piston are balanced when the high pressure piston reaches the end of its power stroke, and are substantially balanced during the power stroke of the low pressure piston which then constitutes the sole means for driving the crosshead.

It is a further object of the invention to provide a fluid pressure engine having connected high pressure and low pressure cylinders with a poppet valve for transferring fluid under pressure from the high pressure cylinder to the low pressure cylinder, and means to balance the pressures on the opposite sides of the poppet valve at the time of opening the poppet valve so that the force required to open the poppet valve is greatly reduced.

it is an object of the invention to provide for the action of the valves in this steam engine a control which is responsive to steam pressure and also to engine speed. In a practice of the invention, such as disclosed herein, the valves are operated by a cam shaft which is axially movable, and means are provided for moving this cam shaft in response to variations of steam pressure and of engine speed.

it is a further object of the invention to provide a vapor engine wherein braking is accomplished by entrapment and compression of vapor, this compression of vapor resulting in a concentration of heat and a rise in the tem perature of the steam, there being means for transmitting the heat from the compressed vapor back into the fluid system of the power plant of which the engine is a part. The heat recovered from the compressed steam employed for braking action is in part transferred to the feed water flowing towards the boiler. The balance is dissipated in the condenser.

It is a further object of the invention to provide a steam power plant wherein spaces for cooling water are provided around the high pressure cylinder and also around the gland through which the high pressure piston rod operates, there being means for including these spaces in the feed water circuit in the power plant.

A further object of the invention is to provide a compound vapor engine of the character referred to in the foregoing having a simple labyrinth seal or gland through which the piston rod of the high pressure piston operates and wherein the normal exhaust vapors and also the vapors which have leaked from the high pressure cylinder into the low pressure cylinder are delivered to the inlet piping of the condenser.

A further object of the invention is to provide a vapor 2,730,996 Patented Jan. 17, 1956 engine, such as a compound steam engine, wherein the crankcase is held at a pressure at least as low as the pressure in the condenser by use of a suitable suction pump, to prevent or minimize passage of oily vapors from the crankcase into the vapor system, so that entry of air and oil into the condenser will be minimized.

A further object of the invention is to provide in this compound vapor engine poppet type high pressure steam inlet and transfer valves, and also a valve which operates to void to the condenser vapor which may have accumulated in the low pressure cylinder, particularly when the engine is running slowly.

it is an object of the invention to provide a compound vapor engine of the character herein set forth having intercommunicating passage means whereby the back face of the high pressure piston and the front face of the low pressure piston are at all times exposed to substantially the same fluid pressure. During braking, the reacting or braking fluid pressure is supplied simultaneously to the front face of the low pressure piston and to the back face of the high pressure piston.

Further objects and advantages of the invention may be brought out in the following part of the specification describing a preferred embodiment of the invention in detail for the purpose of making a complete disclosure without limiting the scope of the invention defined in the appended claims and without limitation of mechanical equivalents to which the claims may be entitled.

Referring to the drawings which are for illustrative purposes only:

Fig. l is a cross-sectional view through one of the cylinder sections of a vapor engine embodying the invention;

Pig. 2 is a fragmentary sectional view taken substantially as indicated on the line 2-2 of Fig. l to show the vaives for controlling the flow of vapors in the section of a vapor engine;

Fig. 3 is a schematic sectional view showing the cam shaft and also means for axial adjustment of the same; and

Fig. 4 is a diagram of the power plant which includes the steam engine illustrated in the foregoing figures.

Referring to Fig. 1, the improved engine includes a crankcase 10 to which a low pressure cylinder 11 is secured by bolts 12. On the lower portion of the cylinder 11 there is a jacket 13 forming a chamber 14. A low pressure cylinder head 15 is secured to the upper end of the cylinder 11, and a high pressure cylinder liner 16 is supported coaxially of the low pressure cylinder 11 by the high pressure cylinder 17 and high pressure cylinder head 19. The high pressure cylinder 17 has an inlet port 20 near its lower end and an outlet port 21 near its upper end, these ports being connected by a helical passage 22 formed between the high pressure cylinder liner if and the high pressure cylinder 17 by cutting a helical groove in the external surface of the high pressure cylinder liner 16. A seal 23 is disposed around the upper portion of the high pressure cylinder liner E6 and the high pressure cylinder head 19 is so formed with relation to the upper extremity 24 of the cylinder liner 16 as to provide an annular space or passage 25 between the parts 19 and 24, the purpose of which will be explained in the following.

The low pressure cylinder head 15 has therein a passage 26 which connects the lower end of the high pressure cylinder 16 with a valve chamber 27 formed in a laterally extending portion 28 of the cylinder head 15. The Valve chamber 27 communicates through a transfer valve port 29 with a passage 39 leading into the upper end of the low pressure cylinder 11. The valve chamber 27 also communicates through a passage 31 with a high pressure inlet valve port 32 arranged to be closed and opened by a high pressure inlet valve poppet 33 having a stem 34 which projects down through a valve guide'35 in alignment with a valve lifter 36 arranged to be actuated by cam shaft C having a cam 37 which engages a roller 33 disposed at the lower end of the lifter 36.

A transfer poppet valve 39 is arranged to control flow through the valve port 29. This poppet valve 39 has a downwardly projecting stem 40 which slides in a valve guide 41 and is arranged to be periodically lifted by a valve lifter 42 which is slidable in a guide 43 and is arranged to be actuated by a cam 44 which engages a roller 45 supported at the lower end of the lifter 42. in Fig. l

is shown the manner in which the passage 30 is formed between the extension 28 of the cylinder head 15 and a lateral extension 46 of the upper portion of the low pressurecylinder 11. in the extension 46 there is an auxiliary valve port 47, substantially aligned with the valve port 32, which communicates through a passage 43 with the 'vapor return line 191 (Fig. 4) leading to the condenser 1% to which the engine is connected or to other vapor disposal. An auxiliary exhaust valve 49, of poppet type,

. is arranged to control flow of fluid through the port 47.

This valve .49 has a stem guided in substantial alignment with the stem 340i the poppet valve 33, and the valve 49 and its stem are disposed between the lower end of the valve stem 34 and the valve lifter 36 so that the cam 37 acts, in addition to its opening of the valve 33, to open the auxiliary exhaust valve 49 and thereby exhaust steam which may leak into the upper portion of the low pressure cylinder 11, thus limiting the low pressure compression. 7

A crankshaft 6, supported for rotation in the crankcase it), provides a crank 61 from which a connecting rod 62 extends upwardly into the low pressure cylinder 11. A cross head 63 is connectedto the upper end of the connecting rod 62 by a wrist pin 54 and a low pressure piston 65 is directly secured to the upper end of the cross head 63 by screws 66, this piston as carrying a plurality of piston rings 57 for sealing engagement with the inner surface of the cylinder 11.

A high pressure piston rod 68 is held in transverselyslidahle en agement with the upper end of the cross head 63 by low pressure piston 65. This piston rod 68 projects upwardly through a gland as, which is supported in axial position by the low pressure cylinder head 15, into the high pressure cylinder 17. A high pressure piston 79 is' screwed onto the upper end of the piston rod es and is fixed thereon by lock screw means 71. The high pressure cylinder head 19 is so formed with relation to the upper portion of the high pressure piston 76 and the lock screw means 71 as to provide a very narrow space or chamber 72 between the cap 1? and the back face of the piston 7 0, which may be regarded as including its locking means 71, when the piston 70 is at the extreme end of its power stroke, or in other words is raised to the position in which it is shown in full lines in Fig. 1. The chamber 72 has a slight annular enlargement 73 at the bottom thereof, and this annular enlargement 73 is connected to the upper end of the low pressure cylinder 11 by a duct 74. A plurality of terminal ports 75 connect the space 72 with the upper portion of the high pressure cylinder 16. These ports 75 are positioned so that they will be uncovered when the piston 7i reaches the end of its power stroke,

as shown in Fig. 1.

The gland or guide as through which the piston rod 68 moves has a plurality of annular grooves 77 therein so as to provide a labyrinth seal around the rod 68 between the low pr ssure cylinder 11 and high pressure cylinder liner to. in the side wall of the low pressure cylinder 11 there is a terminal exhaust port 7 8 adapted to be connected to a condenser or other means of disposal for the exhaust vapors. Above the ten rinal exhaust port 7 8, the side wall has a braking fluid inlet port 7 9 arranged to be connected to a source of vaporunder pressure by duct means as shown in part at 89. The cylinder head 15 is formed so as to provide a space for cooling water around the gland 69, and this space 81 is connected with the inlet port 20 by a duct 82, and a duct 33 is formed in the cylinder head 15 so as to carry the cooling liquid away from the space. 81.

In Fig. 1 the high pressure piston "iii is shown at the end of its power stroke, having uncovered ports 75, just prior to the opening of the transfer valve 39. It will be understood that the piston has moved upwardly into the position in which it is shown in Fig. 1 from a position to act upon the front face 84 of the piston 79 during the remainder of its power stroke. The opening of the ports 75 by the piston 7% as it moves into the extreme position in which it is shown, results in a blast of steam outward into thelower part 73 of the chamber 72 and down through the duct 74 into the upper end of the cylinder 11 so that vapor pressure will be built up against the front face 85 of the low pressure piston 65 and also in the passage 3% where this pressure will act upwardly against the exposed lower face of the poppet valve 39, reducing to a material extent the force which must be exerted by the cam 44 to lift the valve 39 so that steam may flow from the lower end of the high pressure cylinder 17 through the passage 26, the valve port 29 and the passage 30 into the upper end of the low pressure cylinder li where the steam may then expand so as to force the piston 65 downward through the power stroke thereof. During this time the pressure in the space 72 against the back face 7250f the piston 79 will be substantially the same as the pressure in the cylinder 17 below the piston .70, and when the piston 7% passes downwardly below the port 75 transfer valve 39 will be open and the pressure in the space above the low pressure piston will be transmitted through the passage 74- so that the pressures on opposite ends of the high pressure piston are substantially balanced during the power stroke of the low' pressure piston 65. Expansion of the steam within the low pressure cylinder 11 continues until the upper end of the piston 65 uncovers the mouth of the terminal exhaust port 78'whereupon the steam at low pressure is exhausted to the conduits leading to the condenser. The ending of the operating cycle includes the closing of the transfer valve 3%, at a time prior to the uncovering of terminal port 7 8 and the opening of the high pressure inlet valve 32 at the start of the succeeding cycle.

Braking of the engine is accomplished by admitting vapor, such as steam through the inlet port 7? when the piston 65 is moving upwardly with its upper end positioned below the port 79. The admitted steam is compressed'rwithin the cylinder Fill and also travels through the duct 74 into the upper end of the cylinder 17 where it is compressed also by piston 749 so that the admitted braking steam'then reacts downwardly against the front face or end of the low pressure piston 65 and against the back end of the high pressure piston 70.

The steam power system forming a part of my present invention is shown in Fig. 4. The system includes a condenser 10% which is connected to the terminal exhaust port 78 and also to the exhaust passage 48 by'exhaust piping 181. Feed water from the condenser is pumped through conduit 103 by means of feed pump 103a to the inlet port 29 of the cooling system of the engine E. In passing through the cooling spaces $1 and 22 of the engine, the feed water is heated as a part of its function of keeping the frictionally operating walls 16 and 69 at a temperature sufficiently low to enable lubrication thereof. Accordingly, the heat thus extracted is returned into the system. The outlet port 21 of the cooling system is connected through piping 104 with a steam boiler 106 having a steam delivery pipe 107 leading therefrom. A throttle valve 108 connects this pipe 107 through a pipe 109 with the high pressure steam inlet of the engine E and a brake valve 110 is connected to the steam delivery pipe 107 and to the braking inlet 79 by duct 111. Some of the heat of the steam employed for braking purposes in the engine is returned into the system. As the pistons 65 and 70 move upwardly after the admission of steam through the inlet 79, the steam thus admitted is compressed so that the temperature thereof is raised. Some of the heat from this compressed steam is transmitted through some of the engine Walls to the feed water which is moving through the cooling spaces of the engine. The power system also includes a suction pump 114 which is connected through the crankcase by duct means 115. This pump 114 creates a partial vacuum within the crankcase 10 and continuously draws off air and oily vapors which would otherwise find their way into exhaust port 78, thereby minimizing contamination of the exhaust steam with air and oil vapors.

Piping connects the pipe 109 with a cylinder 11% disposed at one end of the cam shaft C as further shown in Fig. 3. In Fig. l a single cylinder and piston section of the engine is shown. In keeping with accepted practice, a number of these sections may be employed, but the explanation of the details of a single section, with its valves, comprehends the complete steam engine. The cylinder 118 has therein a piston 119 which is connected to the leftward end of the cam shaft C as schematically indicated at 120. The piping 116 is connected to the cylinder 118 so that it will shift the piston 119 and the cam shaft C leftwardly against the pressure of a spring 121 and also against a variable fluid force which is applied to the leftward face of a piston 122 disposed in a cylinder 123 at the opposite end of the cam shaft C and being connected thereto by a connection 124. The fluid pressure in the pressure chamber 125 of the cylinder 123 bears a predetermined relation to the speed of the crankshaft of the engine. This relation is one wherein increase in engine speed produces an increase in the fluid pressure in the chamber 125. One manner of accomplishing this result is disclosed in Fig. 3. A positive displacement pump 126 is driven by the crankshaft of the engine so that the volume of liquid displaced from a reservoir 127 through piping 128 into the leftward end of the cylinder 125 will vary in relation to engine speed. A relief passage 129 connects the cylinder 125 with the drain passage 129a.

In Fig. 3, the cam shaft C is shown in a normal drive position. That is to say, it may be assumed that the vehicle carrying the engine has been accelerated to a desired speed. At this time the steam requirements of the engine are relatively small as compared to its requirements under full load conditions. The steam pressure delivered by the throttle 103, Fig. 4, into the pipes 109 and 116 is reduced with relation to the pressure developed in the chamber 125, Fig. 3, the result being that the cam shaft C has been shifted rightwardly so that the cam 37 which actuates the steam inlet poppet valve 33 is in a position of shortened cut-ofi. That is to say, the supply of steam through the inlet valve 33 is cut off greatly in advance of the time it is cut off when the engine is operating under conditions of high power.

However, should the operator of the engine require more power, he may open the throttle 108 a desired amount, thereby increasing the pressure in the pipes 109 and 116. The resulting increase in pressure in the cylinder 118 will cause the piston 119 to move leftwardly, thereby moving the cam 37 leftwardly so that it will retard the inlet steam cut-off and so that steam will be fed into the high pressure cylinder for a longer period of time during the high pressure power stroke of the high pressure piston 70. It will be perceived that the position of the cam shaft C is varied in accordance with changes in fluid pressure in the cylinders 118 and 123 and that these pressures in the cylinders 118 and 123 are related to the factors of steam pressure and engine speed. When the throttle 108 is closed thus stopping the supply of steam to the pipes 109 and 116, the spring 121, Fig. 3, will move the cam shaft C into the starting position. if, at this time, the brake valve 110 is actuated so as to admit steam to the low pressure cylinder 11, above the low pressure piston and high pressure piston such steam will be trapped therein. In view of the fact that at this time the auxiliary exhaust valve 49, working in timed relation to the high pressure inlet valve 33, closes at an advanced or early point in the upward movement of the pistons 65 and 70 and remains closed until the beginning of the next cycle of operation, the resultant braking compression is of maximum effectiveness.

The cam shaft C is provided with reversing cams 131 and 132 spaced rightwardly from and oriented substantially 180 from the respective cams 37 and 44. For use in reversing operation of the engine a slide valve 133 is provided having a movable closure member 134 normally positioned so that its passage 135 will permit flow through the duct 128, as shown. When the closure member 134 is moved leftwardly into its opposite extreme position, the passage 135 thereof will be'aligned with a duct 136 extending from the chamber 125 so that fluid pressure is released from the chamber 125. As schematically indicated the closure 134 has a connection 137 with a slide valve closure 138 having a pair of passages 139 and 140. When the slide valve closure 138 is in its extreme rightward position the passage 139 will be aligned with the duct 116 permitting flow of steam therethrough, and when the closure 138 is shifted to its extreme leftward position the passage 140 thereof will be aligned with the passage 116, permitting flow of steam therethrough into the cylinder 118. When the closure 138 is in an intermediate position (neutral position) a passage 141 formed in the intermediate portion thereof will connect a drain pipe 142 to that portion of the passage 11d extending to the cylinder 11%. When the operator desires to reverse the engine he shifts the lever 145 leftwardly from the position in which it is shown, thereby shifting the slide valve closures 134 and 138 into their extreme leftward positions. This will result in releasing all fluid pressure from the chamber 125 whereupon steam pressure applied to the cylinder 118 will shift the cam shaft C to its extreme leftward position wherein the reverse cams 131 and 132 will be respectively aligned with the rollers 38 and 45 disposed at the lower end of the lifters 36 and 42, whereby reversing admission of steam into the engine is effected.

I claim:

1. In a steam engine: a low pressure cylinder having a head at the outer end thereof and having a braking steam inlet; a low pressure piston operative in said cylinder; a rod extending from said piston through said head; a high pressure piston connected to the outer end of said rod; a high pressure cylinder receiving the high pressure piston, said high pressure cylinder having terminal port means near the outer end thereof adapted to be uncovered by said high pressure piston; duct means for connecting said terminal port means with said low pressure cylinder; high pressure steam inlet valve means arranged to deliver steam into said high pressure cylinder when said high pressure piston is at a position near the beginning of its pressure stroke; transfer valve means adapted to connect said high pressure cylinder to said low pressure cylinder during the return stroke of said high pressure piston and the power stroke of said low pressure piston; means arranged to exhaust steam from said low pressure cylinder at the end of the power stroke thereof; and means, including a brake valve, operable independently of said high pressure steam inlet valve means to deliver braking steam to said low pressure cylinder.

2. In a steam engine: a low pressure cylinder having a head at the outer end thereof; a low pressure piston operative in said cylinder; a rod extending from said piston throughsaid head; a high pressure piston connected to the outer end of said rod; a high pressure cylinder receiving the high pressure piston; high pressure steam inlet valve means arranged to deliver steam into said high pres sure cylinder when said high pressure piston is at a position near the beginning of its pressure stroke; transfer valve means including a poppet valve element, adapted to connect said high pressure cylinder to said low pressure cylinder during the return stroke of said high pressure piston and the power stroke of said low pressure piston; means arranged to exhaust steam from said low pressure cylinder at the end of the power stroke thereof; and means adapted to apply steam pressure to the back face of said poppet valve element to assist in the opening of the same.

3. In a steam engine: a low pressure cylinder having a head at the outer end thereof; a low pressure piston operative in said cylinder; a rod extending from said piston through said head; a high pressure piston connected to the outer end of said rod; a high pressurecylinder receiving the high pressure piston; high pressure steam inlet valve means arranged to deliver steam into said high pressure cylinder when said high pressure piston is at a position near the beginning of its pressure stroke; means adapted to apply steam pressure to the outer end of said high pressure piston during its return movement; transfer valve means including a poppet valve element, adapted to connect said high pressure cylinder to said low pressure cylinder during the return stroke of said high pressure piston and the power stroke of said low pressure piston; means arranged to exhaust steam from said low pressure cylinder at the end of the power stroke thereof; and means adapted to apply steam pressure to the back face of said poppet valve element to assist in the opening of the same.

4. In a steam engine: a low pressure cylinder having a head at the outer end thereof; a low pressure piston operative in said cylinder; a rod extending from said piston through said head; a high pressure piston connected to the outer end of said rod; a high pressure cylinder receiving the high pressure piston; high pressure steam inlet valve means arranged to deliver steam into said high pressure cylinder when said high pressure piston is at a position near the beginning of its pressure stroke; means adapted to apply steam from the interior of said high pressure cylinder to the outer end of said high pressure piston to substantially balance the pressures on the opposite ends of said high pressure piston during its return stroke; transfer valve means including a poppet valve element, adapted to connect said high pressure cylinder to said low pressure cylinder during the return stroke of said high pressure piston and the power stroke of said low pressure piston; means arranged to exhaust steam from said low pressure cylinder at the end of the power stroke thereof; a scavenging valve arranged to connect said low pressure cylinder to the exterior during the return 7 stroke of said low pressure piston; and means adapted to apply steam pressure to the back face of said poppet valve element to assist in the opening of the same.

5. In a steam engine: a low pressure cylinder having a head at the outer end thereof; a low pressure piston operative in said cylinder; a rod extending from said piston through said head; a high pressure piston connected to the outer end of said rod; a high pressure cylinder receiving the high pressure piston, said high pressure cylinder having a terminal port means near the outer end thereof adapted to be uncovered by said high pressure piston; duct means for connecting said terminal port means with said low pressure cylinder; high pressure steam inlet valve means arranged to deliver steam into said high pressure cylinder when said high pressure piston is at a position near the beginning of its pressure stroke; transfer valve means adapted to connect said high pressure cylinder to said low pressure cylinder'during the return stroke of said high pressure piston and the power stroke of said low pressure piston; means arranged to exhaust steam from said low pressure cylinder at the end of the power stroke thereof; and brake means arranged to admit steam into said low pressure cylinder to act against movement of said low pressure piston during its return stroke.

6. in a steam engine: a low pressure cylinder having a head at the outer end thereof; a low pressure piston operative in said cylinder; a rod extending from said piston through said head; a high pressure piston connected to the outer end of said rod; a high pressure cylinder receiving the high pressure piston, said high pressure a cylinder having terminal port means near the outer. end

thereof adapted to be uncovered by said high pressure piston; duct means for connecting said terminal port means with said low pressure cylinder; high pressure steam inlet valve means arranged to deliver steam 'into said high pressure cylinder when said high pressure piston is at a position near the beginning of its pressure stroke; transfer valve means adapted to connect said high pressure cylinder to said low pressure cylinder during the return stroke of said high pressure piston and the power stroke of said low pressure piston; meansarranged to exhaust steam from said low pressure cylinder at the end of the powerstroke thereof; a tubular sealing means round said rod in a position between said cylinders,

there being Walls forming a cooling chamber in cooling relation to said tubular sealing means; and means forming inlet and outlet passages for said cooling chamber so said high pressure cylinder when said high pressure piston is at a position near the beginning of its pressure stroke; transfer valve means adapted to connect said high pressure cylinder to said low pressure cylinder during the return stroke of said high pressure piston and the power stroke of said low pressure piston; means arranged to exhaust steam from said low pressure cylinder at the end of the power strokethereofi'a tubular sealing means around said rod in a position between said cylinders, there being walls forming a cooling chamber in cooling relation to said tubular sealing means; and means forming inlet and outlet passages for said cooling chamber so that water may be passed therethrough to cool said tubular sealing means.

References Cited in the file of this patent UNITED STATES PATENTS Mueller Oct.,.23, 1951 

